Field of the Invention
The present invention relates to an electromagnetic wave absorber, in particular a radio wave absorber that absorbs radio waves, and to a film forming paste that can be preferably used for forming an radio wave absorbing film in the radio wave absorber.
Related Art
A high frequency band is increasingly being used in various information communication systems such as cellular telephones, wireless LANs, ETC systems, intelligent transport systems, driving support road systems, satellite broadcasting and the like. However, increasing use of radio waves of the high frequency band involves risk of failure and malfunction of electronic devices due to interference between electronic devices. In order to address such a problem, a method of absorbing unnecessary radio waves by a radio wave absorber has been employed.
Among the uses of the high frequency band radio waves, advanced research has been conducted with regard to driving support systems for automobiles. In such driving support systems for automobiles, a radio wave of a 76 GHz band is used in an in-car radar for detecting a distance between cars and the like. Use of the high frequency band radio waves, for example 100 GHz or higher, is expected to be widespread for various purposes, and not limited to driving support systems for automobiles. As a result, a radio wave absorber that can preferably absorb radio wave of a band of 76 GHz or higher is desired.
In order to meet such a demand, for example, a radio wave absorber provided with a radio wave absorbing film containing magnetic crystals consisting of ε-Fe2O3 based iron oxide has been proposed as a radio wave absorber that can preferably absorb radio waves over a broad range in a high frequency band (refer to Japanese Unexamined Patent Application Publication No. 2008-277726).